Navistar demonstrated the technology in an International rear engine school bus fitted with an International T444E diesel engine and a continuously regenerating trap (CRT). The bus was fueled with ultra-low sulfur diesel fuel of less than 5 ppm S, which is required for proper operation of the CRT trap.

Particulate matter emissions were reduced by more than 90%, resulting in emission levels that were 50% lower than the best 1998 certified compressed natural gas engine. According to Navistar, hydrocarbons were reduced below measurable levels and the diesel odor was eliminated.

Navistar said, if ultra-low sulfur diesel fuel is available, the technology can be applied to pickups, heavy trucks, and sport utility vehicles, which are subject to the proposed Tier 2 emission standards.

"Industry is not alone in recognizing the benefits of diesel engines," said Pat Charbonneau, vice president of engine engineering for Navistar's Engine and Foundry Division. "The Administration's Partnership for a New Generation of Vehicles is focused on diesel engines as the leading candidate for achieving greatly increased fuel economy without burdening consumers with added costs or reduced convenience."

"Ultra-clean diesel fuel is an absolute necessity if we are going to achieve the dramatic breakthroughs necessary to reduce nitrogen oxides and particulate emissions," Charbonneau said. "All of our research and development work rests on the premise that low-sulfur fuel is a critical technology enabler without which we cannot achieve the level of nitrogen oxides and particulate matter control called for by the Tier 2 proposal," he emphasized.